Dust is not only an annoyance gloaming on to stuff and making us sneeze.  It can be dangerous if it gets into the air and there is a lot of it.  At the nanometer scale, things are different and things that can burn—burn a lot faster.  It is the way the engine in a car works, tiny droplets of gasoline burn really fast in the cylinders of the engine.  Even things as innocent as sugar can become explosive if tiny particles become airborne.  Now scientists have shown that nanodust is even more explosive than just regular dust.  As the size of something is reduced its surface area gets larger.   It takes a lot less energy to ignite the material and so it can be made to burn a lot easier.  Nobody is sure if this makes the manufacturer of nanomaterials more dangerous but for the past few hundred years the dangers from exploding flour in mills has been well known.
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